Interconnecting the overlay networks of multiple organizations within a data network becomes a fundamental requirement, as overlay networks proliferate in number. The number of organizations having virtualized overlay networks continues to grow and the requirements on the mechanisms used to provide this interconnectivity in a scalable manner become critical to the success of these virtualized networks.
In the simplest interconnectivity model, an overlay would be fully terminated at the edge of an organization and mapped to a different overlay that is managed by either a peer organization or a service provider of data transit services. In either case, the edge devices between organizations must maintain the full state of all routes for all organizations that are peering to each other. As mobility becomes more widely adopted, the routing information for the different organizations becomes very granular and does not benefit from summarization in an edge device. The net result is an explosion in the amount of states and information that an edge device must maintain.